Well, at least you are narrowed down to 2. The L or XL. I'm 5'11" and the L fit me perfect.
From there you really should test ride. Start with the L but if you're long torso'd the effective TT could make you feel a bit cramped.

I am on a large SL and regret not going XL. I am in the middle of planning to swap frames for an HD and will likely be going XL on that. I am 6'1ish. Test riding both is really the only way to know for sure which you need to go with

It's a tough one.
We are same height and Ibis told me to go L but I went XL.
Now I'm wondering if I should have gone with L.
If you purchase from competitive cyclist they have a no questions asked return policy on bikes.

I'm 6.1 and ride an XL SLR. I originally bought an L thinking an XL would be too big, since I used to ride a Stumpy L. But Ibises are smaller than the average bike. After riding it for just a few minutes I realized it was too small, and tweaking it with longer stems or offset seatposts would just make a goat look like an elephant. Try to find your current bike's real measurements online, and then compare.

I'm 6'1". I thought I was on the border, I went with the L and it actually feels big. Yes, I have an angleset on it so it has a longer wheel base. And yes I'm running wide bars, but I'm also running a 70mm stem and looking to get a 50mm.

I know the geo chart makes the TT seem short, but it feels plenty roomy.

the XL felt great. I was coming off a L Titus El Guapo and they feel very similar. The stem on the Ibis is a big longer than the one on El Guapo... I'm sure some time and some tweaking and she will feel lovely.

Rode the Ibis on my trails today. Light, stiff, and responsive. Much better bike than I am rider.